1. Field of the Invention
The present invention relates to a method of manufacturing a head suspension for a disk drive incorporated in an information processing unit such as a personal computer.
2. Description of the Related Art
A hard disk drive (HDD) used for an information processing unit has magnetic or magneto-optical disks to write and read data and a carriage. The carriage is turned around a spindle by a positioning motor. The carriage is disclosed in, for example, U.S. Pat. No. 4,167,765. This carriage has arms, a head suspension attached to each arm, and a head attached to the suspension and having a slider.
When each disk in the HDD is rotated at high speed, the slider slightly floats above the disk and air bearings are formed between the disk and the slider.
FIG. 1 shows atypical suspension 101 of an HDD. The suspension 101 has a load beam 103. The load beam 103 is fixed to a base plate 105 by, for example, laser welding. The base plate 105 is fitted to a carriage arm of the HDD.
The load beam 103 consists of a rigid part 107 of L1 in length and a resilient part 109 of L2 in length. A flexure 111 is fixed to the rigid part 107 by, for example, laser welding. An end of the flexure 111 has a tongue 113 to which a slider 115 is attached. The tongue 113 is pushed by a dimple 117, which is formed at an end of the rigid part 107. Although the dimple 117 is depicted with a solid line in FIG. 1, it is actually on the back of the tongue 113.
The rigid part 107 is provided with positioning holes 121 and 125, and the flexure 111 is provided with positioning holes 123 and 127.
The holes 121, 123, 125, and 127 are set on positioning pins of a jig to align the rigid part 107 and flexure 111 with each other, and the rigid part 107 and flexure 111 are fixed to each other by, for example, laser welding. The positioning and fixing of the flexure 111 to the rigid part 107 determine the vibration characteristics of the suspension 101.
Disks of recent HDDs are designed to densely record data and revolve at high speed. It is required, therefore, to provide a suspension of improved vibration characteristics to carry out precision positioning of a head on an HDD disk surface, To meet the requirement, the suspension 101 must be compact. Namely, the distance A between the dimple 117 and a fitting center of the base plate 105 must be short. The distance A, however, must sufficiently be long to secure a proper distance between the holes 121 and 125 for correct positioning of the flexure 111 with respect to the rigid part 107.
If the distance A is excessively shortened to improve vibration characteristics, the holes 121 and 125 will be too close to each other, thereby deteriorating positioning accuracy.
To solve this problem, FIGS. 2A to 2C show a head suspension 101A for a disk drive according to a prior art. This prior art forms a positioning hole 125 on the side of a base plate 105. Even if the distance A (FIG. 1) between a dimple 117 and a fitting center of the base plate 105 is short, a sufficient distance is secured between positioning holes 121 (123) and 125 (127) for correct positioning of a flexure 111 to a rigid part 107.
Formation of the suspension 101A will be explained FIG. 2A is a plan view showing parts of the suspension 101A before assembly, and FIG. 2B is a plan view showing the parts after assembly. In FIG. 2A, the flexure 111 is provided with the positioning holes 123 and 127. The base plate 105 is fitted to a reinforcing plate 129. The reinforcing plate 129 is solidly joined with the rigid part 107 of a load beam 103 through a bridge 131, to form a semi-finished suspension 133. The rigid part 107 is provided with the positioning bole 121, and the reinforcing plate 129 with the positioning hole 125.
A resilient material 135 is used to form a resilient part 109 of the load beam 103. The resilient material 135 is placed over the rigid part 107 and reinforcing plate 129 and is fixed thereto by, for example, laser welding. Thereafter, the base plate 105 is fitted to the reinforcing plate 129 and is fixed thereto by, for example, laser welding
The semi-finished suspension 133 with the resilient material 135 and base plate 105 is set on a jig by passing pins of the jig through the holes 121 and 125, and the flexure 111 is laid thereon by passing the jig pins passed through the holes 121 and 125 through the holes 123 and 127 respectively. This precisely positions the flexure 111 with respect to the rigid part 107 as shown in FIG. 2B.
The distance between the holes 121 (123) and 125 (127) is appropriate for precision positioning between the rigid part 107 and the flexure 111. Under this state, the flexure 111 is fixed to the rigid part 107 by, for example, laser welding.
Thereafter, the bridge 131 is cut off by, for example, a press, to complete the suspension 101A of FIG. 2C.
One problem of this prior art is to leave the peripheries of the holes 125 and 127 on the base plate 105, to cause a horizontal imbalance on the base plate 105. This imbalance deteriorates the vibration characteristics of the suspension 101A.
An object of the present invention is to provide a method of manufacturing a bead suspension or a semi-finished suspension that is compact, secures a sufficient distance between positioning holes, and involves no base-plate imbalance.
In order to accomplish the object, a first aspect of the present invention provides a method of manufacturing a head suspension for a disk drive. The head suspension has a base plate to be supported by a carriage, a load beam including a rigid part resiliently supported by the base plate, to apply load onto a slider, and a flexure positioned and fitted to the load beam and having a read-write head. The method includes a first step of forming a semi-finished suspension having the base plate, the rigid part solidly joined with the base plate through a bridge, and a protrusion protruding from one of the base plate and rigid part and having a positioning bole to be aligned with a positioning hole formed through part of the flexure, a second step of fixing a resilient material to the base plate and rigid part of the semi-finished suspension so that the base plate may resiliently support the rigid part through the resilient material, a third step of aligning the positioning hole of the flexure with the positioning hole of the protrusion and fixing the flexure to the rigid part, and a fourth step of cutting off the positioning-hole-formed part of the flexure, the bridge, and the protrusion including the positioning hole.
The first aspect may form the positioning hole of the protrusion in the vicinity of the base plate, to secure a proper distance between the positioning hole and a positioning hole formed through the rigid part. This results in precisely positioning the flexure with respect to the rigid part and correctly fixing the flexure thereto. The first aspect cuts off the bridge, the protrusion having the positioning hole, and the positioning-hole-formed part of the flexure. As a result, the suspension manufactured from the semi-finished suspension has no positioning holes including their peripheries, to cause no horizontal imbalance and improve the vibration characteristics of the suspension. In addition, the suspension of the first aspect is compact to further improve the vibration characteristics thereof.
A second aspect of the present invention makes the bridge serve as the protrusion.
The second aspect forms the positioning hole to be aligned with the positioning hole of the flexure on the bridge that solidly joins the rigid part to the base plate. The second aspect provides the same effect as the first aspect.
A third aspect of the present invention forms, in the first step, the positioning hole through one of the protrusion and bridge in the vicinity of the base plate.
The third aspect secures a proper distance between the positioning hole on one of the protrusion and bridge and a positioning hole on the load beam, to correctly position the flexure with respect to the load beam.
A fourth aspect of the present invention provides, in the first step, one of the protrusion and bridge with a corner in the vicinity of the base plate and forms the positioning hole at the corner.
The fourth aspect secures a long distance between the positioning hole on one of the protrusion and bridge and a positioning hole on the load beam, to make the suspension compact and correctly position the flexure with respect to the load beam.
A fifth aspect of the present invention provides a semi-finished suspension used for manufacturing a head suspension for a disk drive. The head suspension has a base plate to be supported by a carriage, a load beam including a rigid part resiliently supported by the base plate, to apply load onto a slider, and a flexure positioned and fitted to the load beam and having a read-write head. The semi-finished suspension has the base plate, the rigid part solidly joined with the base plate through a bridge, and a protrusion protruding from one of the base plate and rigid part and having a positioning hole to be aligned with a positioning hole formed through part of the flexure.
The fifth aspect cuts off the bridge and protrusion so that the base plate may have no positioning holes and their peripheries. As a result, a suspension manufactured from the semi-finished suspension of the fifth aspect involves no horizontal imbalance and shows improved vibration characteristics.
A sixth aspect of the present invention makes the bridge serve as the protrusion.
The sixth aspect forms the positioning hole to be aligned with the positioning hole of the flexure on the bridge that solidly joins the rigid part to the base plate. The bridge is cut off in the last stage so that the base plate may have no positioning holes including the peripheries of the holes. As a result, a suspension manufactured from the semi-finished suspension of the sixth aspect involves no horizontal imbalance and shows improved vibration characteristics.